Physical model test system for simulating strong mine tremors based on joint monitoring of microseismic and acoustic emission and test method thereof

Abstract

A physical model test system for simulating strong mine tremors based on joint monitoring of MS and AE and a test method thereof, comprising: positioning and drilling a circular hole in a load plate according to design positions of all-fiber MS and AE sensors; mounting limiting rings concentric with the circular holes outside the load plates; bonding seismic isolation antifriction plates on inner walls of the load plates; manufacturing model body through layered compaction method to a height reaching one of the circular holes; inserting wave conducting rod into the limiting ring and the circular hole sequentially to a specified depth of the model body; filling with analogue materials and compacting; detaching the limiting rings after the model body is stably loaded, connecting the all-fiber MS sensors to exposed portion of the wave conducting rod, and bonding the AE sensors to outer sidewalls of the wave conducting rods.

1 . A physical model test system for simulating strong mine tremors based on joint monitoring of microseismic (MS) and acoustic emission (AE), comprising a model test rack, wherein a plurality of hydraulic jacks are mounted on an inner wall of the model test rack, to drive load plates applying a load to a model body; wave conducting rods, wherein a built-in portion of each of the wave conducting rods is inserted inside the model body, and an exposed portion of the each of the wave conducting rods extends to an outer side of the load plate; all-fiber MS sensors are installed at ends of exposed sections of the wave conducting rods, with AE sensors attached to outer sidewalls of the wave conducting rods, wherein the all-fiber MS sensors are connected to an all-fiber MS monitoring system, and the AE sensors are connected to an AE system; and, monitoring elements for monitoring stress, strain, and displacement are further provided in the model body, and the monitoring elements are connected to a corresponding test system, respectively. 
     
     
         2 . The physical model test system according to  claim 1 , wherein the load plate is manufactured by cutting a uniform and flat thick steel plate, and comprises a sheet-type load plate, a block-type load plate, and an integral-type load plate. 
     
     
         3 . The physical model test system according to  claim 2 , wherein the integral-type load plate is located at a bottom of the model body; the sheet-type load plates are located on left, right, and rear side surfaces of the model body, respectively; and, the block-type load plates are located on a top surface of the model body. 
     
     
         4 . The physical model test system according to  claim 2 , wherein positions of the all-fiber MS and AE sensors in space cannot be coplanar. 
     
     
         5 . The physical model test system according to  claim 1 , wherein seismic isolation antifriction plates are provided on inner walls of the load plates. 
     
     
         6 . The physical model test system according to  claim 1 , wherein circular holes are drilled in the load plates, and detachable-type limiting rings that are concentric with the circular holes are provided on outer surfaces of the load plates and are fixed by limiting bolts; and, a diameter of each of the circular holes is greater than an inner diameter of each of the limiting rings, and the inner diameter of the each of the limiting rings is greater than an outer diameter of the each of the wave conducting rods. 
     
     
         7 . The physical model test system according to  claim 1 , wherein the each of the wave conducting rod is of a regular prism shape, and a width of one of four outer sidewalls of the each of the wave conducting rods is greater than a diameter of each of the AE sensors, and the exposed portions of the wave conducting rods are processed with threads matching the all-fiber MS sensors. 
     
     
         8 . The physical model test system according to  claim 1 , wherein acrylic plates are provided on a front surface of the model test rack, and are closely attached to the front surface of the model body. 
     
     
         9 . The physical model test system according to  claim 1 , comprising sheet-type latticed-type steel bridges that are hollow in the middle and closed at two ends and are connected by bolts, a pull-out-type front wall, and an acrylic plate, wherein the latticed-type steel bridges may be freely assembled to adapt to coal seams mining model tests under different similar scales; the pull-out-type front wall of the model test rack is provided inside the assembled steel bridges, and is to provide a passive constraint for the model body and reserves an operation space for the simulation of the coal seam mining; and the acrylic plate is provided in a groove of the assembled steel bridges and is configured for providing a passive constraint for the model body and implementing visualized observation of the simulation of the overburden breaking. 
     
     
         10 . A test method by using a physical model test system for simulating strong mine tremors based on joint monitoring of MS and AE according to  claim 1 , comprising:
 choosing a coordinate origin, and establishing a space rectangular coordinate system;   determining a spatial layout plan of all-fiber MS sensors and AE sensors; and   determining 3D coordinates of the all-fiber MS and AE sensors by using the established space rectangular coordinate system as a reference;   drilling circular holes on load plates according to the determined spatial layout plan, and installing detachable-type limiting rings concentric with the circular holes outside the load plates and securing by limiting bolts;   manufacturing a model body by using a layered compaction air-drying method with a height to reach one of the circular holes, then inserting wave conducting rods sequentially into the limiting rings and the circular holes of the load plates to a specified depth inside the model body, and filling with analogue materials and compacting;   bonding the AE sensors at the specified position in outer sidewalls of the wave conducting rods, and screwing the all-fiber MS sensors into ends of the wave conducting rods;   determining whether a MS-AE positioning error meets an accuracy requirement by carrying out a knock positioning test; and   if the accuracy requirement is met, then performing the model test, and monitoring and acquiring MS and AE events in real time; otherwise, checking and repairing an all-fiber MS monitoring system, an AE system, and corresponding sensors, and then carrying out the knock positioning test again until the positioning error meets the accuracy requirement.